National Retail Federation revises down 2015 US retail sales forecast

The Nation Retail Federation on Wednesday revised down its forecast for 2015 retail sales and said it expects back-to-school revenues to fall from last year.

The industry association anticipates retail sales growth of 3.5 percent this year, down from an earlier estimate of 4.1 percent. It cited "unexpectedly slow growth" during the first half of the year due to factors including treacherous winter weather and the West Coast port shutdown.

Households are also spending a growing share of their income on services rather than goods, the federation said.

"It's a little bit like deja vu all over again. We did that last summer," federation President and CEO Matthew Shay told CNBC's "Squawk Box."

The average family is expected to spend $630 on back-to-school supplies this year, compared with $669 last year.

"We think the numbers are a little bit down because people have replenished last year," Shay said.

Slightly higher growth in the second half of 2015 should offset a slow start to the year, the NRF said. Its estimate accounts for general retail sales and nonstore sales and excludes automobiles, gas stations and restaurants.

Shay said politicians should focus on implementing policies that promote growth such as tax reform and infrastructure spending rather than backing proposed increases to overtime pay and the federal minimum wage.